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Azobenzene

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https://www.readbyqxmd.com/read/28902226/thermo-photo-and-mechano-responsive-liquid-crystal-networks-enable-tunable-photonic-crystals
#1
N Akamatsu, K Hisano, R Tatsumi, M Aizawa, C J Barrett, A Shishido
Tunable photonic crystals exhibiting optical properties that respond reversibly to external stimuli have been developed using liquid crystal networks (LCNs) and liquid crystal elastomers (LCEs). These tunable photonic crystals possess an inverse opal structure and are photo-responsive, but circumvent the usual requirement to contain dye molecules in the structure that often limit their applicability and cause optical degradation. Herein, we report tunable photonic crystal films that reversibly tune the reflection peak wavelength under thermo-, photo- and mechano-stimuli, through bilayering a stimuli-responsive LCN including azobenzene units with a colourless inverse opal film composed of non-responsive, flexible durable polymers...
September 13, 2017: Soft Matter
https://www.readbyqxmd.com/read/28902195/driving-and-photo-regulation-of-myosin-actin-motors-at-molecular-and-macroscopic-levels-by-photo-responsive-high-energy-molecules
#2
Halley M Menezes, Md Jahirul Islam, Masayuki Takahashi, Nobuyuki Tamaoki
We employed an azobenzene based non-nucleoside triphosphate, AzoTP, in a myosin-actin motile system and demonstrated its efficiency as an energy molecule to drive and photo-regulate the myosin-actin motile function at the macroscopic level along with an in vitro motility assay. The AzoTP in its trans state induced shortening of a glycerinated muscle fibre whilst a cis isomer had no significant effect. Direct photoirradiation of a cis-AzoTP infused muscle fibre induced shortening triggered by a locally photo-generated trans-AzoTP in the muscle fibre...
September 13, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28900643/unidirectional-rotation-of-cholesteric-droplets-driven-by-uv-light-irradiation
#3
Shinji Bono, Sayumi Sato, Yuka Tabe
We investigated the novel photo-induced dynamics of azobenzene-doped cholesteric (Ch) droplets coexisting with the isotropic (Iso) phase. When the hemispherical Ch droplets initially stuck to glass substrates were irradiated by UV-light, they were parted from the substrates due to the surface disordering caused by the photo-isomerization of azobenzene. Then, the spherical droplets floating in the Iso phase exhibited an unexpected motion - a continuous and unidirectional rotation along the light propagation direction...
September 13, 2017: Soft Matter
https://www.readbyqxmd.com/read/28895267/long-lived-supramolecular-helices-promoted-by-fluorinated-photoswitches
#4
He Huang, Tetiana Orlova, Benjamin Matt, Nathalie Katsonis
Chiral azobenzenes can be used as photoswitchable dopants to control supramolecular helices in liquid crystals. However, the lack of thermal stability of the cis-isomer precludes envisioning the generation of long-lived supramolecular helices with light. Here, this study demonstrates thermally stable and axially chiral azobenzene switches that can be used as chiral dopants to create supramolecular helices from (achiral) nematic liquid crystals. Their trans-to-cis photoisomerization leads to a variation of helical twisting power that reaches up to 60%, and the helical superstructure that is engineered with light displays a relaxation time that reaches tens of hours...
September 12, 2017: Macromolecular Rapid Communications
https://www.readbyqxmd.com/read/28895251/taming-macromolecules-with-light-lessons-learned-from-vibrational-spectroscopy
#5
REVIEW
Jaana Vapaavuori, C Geraldine Bazuin, Christian Pellerin
Exciting new applications, from large-area nanopatterning and templating to soft light-powered robotics, are emerging from the fundamental research on light-triggered changes in macromolecular systems upon photoisomerization of azobenzene-based molecular photoswitches. The understanding of how the initial molecular-scale photoisomerization of azobenzene, a complex photochemical event in itself, is translated into the response of macromolecules and even into macroscopic-scale motion of illuminated azomaterials is an enormous task...
September 12, 2017: Macromolecular Rapid Communications
https://www.readbyqxmd.com/read/28895243/controlling-complex-stability-in-photoresponsive-macromolecular-host-guest-systems-toward-reversible-capture-of-dna-by-cyclodextrin-vesicles
#6
Johanna Moratz, Lucas Stricker, Sabrina Engel, Bart Jan Ravoo
An effective and universal method for delivering structurally diverse biomolecules in vivo would greatly benefit modern drug therapy, but has yet to be discovered. Self-assembled supramolecular complexes containing vesicles of amphiphilic cyclodextrin and linker molecules with an azobenzene guest unit and a charged functionality have been established as nanoscale carriers for proteins and DNA, making use of multivalent electrostatic attraction. However, light-induced cargo release is only feasible up to a maximum net charge of the biomacromolecules...
September 12, 2017: Macromolecular Rapid Communications
https://www.readbyqxmd.com/read/28885845/near-infrared-photoswitching-of-azobenzenes-under-physiological-conditions
#7
Mingxin Dong, Amirhossein Babalhavaeji, Catherine V Collins, Kareem Jarrah, Oleg Sadovski, Qiuyun Dai, G Andrew Woolley
Biological tissue exhibits an absorbance minimum in the near-infrared between 700 and 900 nm that permits deep penetration of light. Molecules that undergo photoisomerization in this bio-optical window are highly desirable as core structures for the development of photopharmaceuticals and as components of chemical-biological tools. We report the systematic design, synthesis, and testing of an azobenzene derivative tailored to undergo single-photon photoswitching with near-infrared light under physiological conditions...
September 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28881057/efficient-sensitized-z%C3%A2-e-photoisomerization-of-an-iridium-iii-azobenzene-complex-over-a-wide-concentration-range
#8
Javier Moreno, Lutz Grubert, Jutta Schwarz, David Bléger, Stefan Hecht
To improve the sensitized Z→E photoisomerization of azobenzenes, and circumvent the threshold concentration necessary for the bimolecular photoinduced electron transfer reaction to generate the rapidly isomerizing Z-azobenzene radical anion, an Ir(III) complex with a covalently tethered azobenzene fragment was synthesized. Selective irradiation of the (1) MLCT band of the Ir(III) complex induced an efficiently sensitized photoswitching of the dyad over a wide concentration range and even at high dilution.
September 7, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28880328/visible-light-temperature-dual-responsive-hydrogel-constructed-by-%C3%AE-cyclodextrin-and-an-azobenzene-linked-surfactant
#9
Jiao Wang, Qintang Li, Sijing Yi, Xiao Chen
A novel photo-responsive anionic surfactant with a dimethylamino-substituted azobenzene located at the end of the hydrophobic chain, 6-(4-dimethylaminoazobenzene-4'-oxy)hexanoate sodium (DAH), has been designed. Through the host-guest interaction in aqueous solution, the trans-DAH could be spontaneously included by using two native α-cyclodextrin (α-CD) molecules. The formed hydrophilic inclusion complex (DAH@2α-CD), however, could act as a gelator to induce the formation of a supramolecular hydrogel, which is driven mainly by hydrogen bonds between neighboring α-CDs and also between the carboxylate in DAH and water...
September 7, 2017: Soft Matter
https://www.readbyqxmd.com/read/28858663/photoswitchable-janus-glycodendrimer-micelles-as-multivalent-inhibitors-of-leca-and-lecb-from-pseudomonas-aeruginosa
#10
Yingxue Hu, Ghamdan Beshr, Christopher J Garvey, Rico F Tabor, Alexander Titz, Brendan L Wilkinson
The first example of the self-assembly and lectin binding properties of photoswitchable glycodendrimer micelles is reported. Light-addressable micelles were assembled from a library of 12 amphiphilic Janus glycodendrimers composed of variable carbohydrate head groups and hydrophobic tail groups linked to an azobenzene core. Spontaneous association in water gave cylindrical micelles with uniform size distribution as determined by dynamic light scattering (DLS) and small angle neutron scattering (SANS). Trans-cis photoisomerization of the azobenzene dendrimer core was used to probe the self-assembly behaviour and lectin binding properties of cylindrical micelles, revealing moderate-to-potent inhibition of lectins LecA and LecB from Pseudomonas aeruginosa...
August 16, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28858420/photoswitchable-carbohydrate-based-macrocyclic-azobenzene-synthesis-chiroptical-switching-and-multi-stimuli-responsive-self-assembling
#11
Juan Xie
A one-pot O-alkylation mediated macrocyclization approach has been used for the synthesis of carbohydrate-based macrocyclic azobenzene. The synthesized macrocycle can be reversibly isomerized between E and Z isomers upon UV or visible irradiation with excellent photostability and thermal stability (t1/2 = 51 days at 20°C for the Z isomer). A chirality transfer from the chiral sugar unit to azobenzene was observed by circular dichroism (CD). DFT and TD-DFT calculations were performed to calculate the optimal geometry and the theoretical absorption and CD spectra...
August 31, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28852067/light-induced-conductance-switching-in-photomechanically-active-carbon-nanotube-polymer-composites
#12
V Schneider, O Polonskyi, T Strunskus, M Elbahri, F Faupel
Novel, optically responsive devices with a host of potential applications have been demonstrated by coupling carbon nanomaterials with photochromic molecules. For light-induced conductance switching in particular, we have recently shown that carbon nanotube-polymer nanocomposites containing azobenzene are very attractive and provide stable and non-degradable changes in conductivity over time at standard laboratory conditions. In these composites, the photoswitching mechanisms are based on light-induced changes in electronic properties and related to the Pool-Frenkel conduction mechanism...
August 29, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28846842/circularly-polarized-light-with-sense-and-wavelengths-to-regulate-azobenzene-supramolecular-chirality-in-optofluidic-medium
#13
Laibing Wang, Lu Yin, Wei Zhang, Xiulin Zhu, Michiya Fujiki
Circularly polarized light (CPL) as a massless physical force causes absolute asymmetric photosynthesis, photodestruction, and photoresolution. CPL handedness has long been believed to be the determining factor in the resulting product's chirality. However, product chirality as a function of the CPL handedness, irradiation wavelength, and irradiation time has not yet been studied systematically. Herein, we investigate this topic using achiral polymethacrylate carrying achiral azobenzene as micrometer-size aggregates in an optofluidic medium with a tuned refractive index...
September 5, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28846399/synthesis-of-azobenzenes-using-n-chlorosuccinimide-and-1-8-diazabicyclo-5-4-0-undec-7-ene-dbu
#14
Alford Antoine John, Qing Lin
A convenient method for the synthesis of symmetrical azobenzenes is reported. This one-step procedure involves treatment of anilines with N-chlorosuccinimide (NCS) and organic base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). A wide range of commercially available substituted anilines readily participate in this reaction to produce the corresponding azobenzenes in moderate-to-excellent yields in minutes.
September 15, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28834432/formation-of-highly-pure-and-patterned-carbon-nanotube-films-on-a-variety-of-substrates-by-a-wet-process-based-on-light-induced-dispersibility-switching
#15
Hirokuni Jintoku, Tadatake Sato, Tomoka Nakazumi, Yoko Matsuzawa, Hideyuki Kihara, Masaru Yoshida
A simple fabrication method for patterned carbon nanotube (CNT) films is presented, using the concept of light-induced dispersibility switching with a photoresponsive dispersant. A comparison with other dispersants highlights the important role played by an azobenzene-derived cationic molecule as a photoisomerizable dispersant in the successful manufacture of patterned CNT films. Upon UV irradiation for a short time (∼0.5 min), a dispersion composed of CNTs and photoresponsive dispersant exhibited a dispersibility change due to the photoisomerization of the photoresponsive dispersant, and then the dispersant detached-CNT deposited onto the substrate...
September 13, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28833610/proof-of-concept-studies-directed-towards-designed-molecular-wires-property-driven-synthesis-of-air-and-moisture-stable-polystannanes
#16
Daniel Foucher, Jeffery Pau, Alan J Lough, Robert Steven Wylie, Robert A Gossage
Polystannanes with azobenzene moieties designed to protect the Sn-Sn backbone from light- and moisture-induced degradation is described. The azo-stannyl precursor 3 (70%) is converted in good yields (88-91%) to the mono- (4), and dichloro- (5) stannanes, by sequential chlorination, followed by further reduction of 5 to the dihydride (6) using NaBH4 (78%). All stannanes were characterised by NMR (1H, 13C, 119Sn) spectroscopy and HRMS; in addition, 3, 4 and 5 were structurally elucidated via X-ray diffraction analysis...
August 21, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28832166/photoisomers-of-azobenzene-star-with-a-flat-core-theoretical-insights-into-multiple-states-from-dft-and-md-perspective
#17
Markus Koch, Marina Grenzer Saphiannikova, Svetlana A Santer, Olga A Guskova
This study focuses on comparing physical properties of photoisomers of an azobenzene star with benzene-1,3,5-tricarboxamide core. Three azobenzene arms of the molecule undergo a reversible trans-cis isomerisation upon UV-vis light illumination giving rise to multiple states from the planar all-trans one, via two mixed states to the kinked all-cis isomer. Employing density functional theory, we characterize the structural and photophysical properties of each state indicating a role the planar core plays in the coupling between azobenzene chromophores...
August 23, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28825625/synthesis-and-antimicrobial-studies-of-new-antibacterial-azo-compounds-active-against-staphylococcus-aureus-and-listeria-monocytogenes
#18
Stefano Piotto, Simona Concilio, Lucia Sessa, Rosita Diana, Gabriel Torrens, Carlos Juan, Ugo Caruso, Pio Iannelli
Some novel (phenyl-diazenyl)phenols (4a-m) were designed and synthesized to be evaluated for their antibacterial activity. Starting from an active previously-synthesized azobenzene chosen as lead compound, we introduced some modifications and optimization of the structure, in order to improve solubility and drug conveyance. Structures of all newly-synthesized compounds were confirmed by ¹H nuclear magnetic resonance (NMR), mass spectrometry, and UV-Vis spectroscopy. Antibacterial activity of the new compounds was tested with the dilution method against the bacteria strains Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa PAO1...
August 19, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28820237/conformal-silk-azobenzene-composite-for-optically-switchable-diffractive-structures
#19
Giovanna Palermo, Luca Barberi, Giovanni Perotto, Roberto Caputo, Luciano De Sio, Cesare Umeton, Fiorenzo G Omenetto
The use of biomaterials as optical components has recently attracted attention because of their ease of functionalization and fabrication, along with their potential use when integrated with biological materials. We present here an observation of the optical properties of a silk-azobenzene material (Azosilk) and demonstrate the operation of an Azosilk/PDMS composite structure that serves as a conformable and switchable optical diffractive structure. Characterization of thermal and isomeric properties of the device, along with its overall performance, is presented in terms of diffractive characteristics and response times...
September 13, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28815793/responsiveness-and-morphology-study-of-dual-stimuli-controlled-supramolecular-polymer
#20
Chenxiao Xiong, Meiran Xie, Ruyi Sun
The synthesis and characterization of a linear supramolecular polymer formed by dual host-guest recognitions is presented. The polymer linked by the orthogonal interactions of azobenzene with β-cyclodextrin and methyl viologen with sulfonatocalix[4]arene is constructed, and the morphology change along with the formation and vanishment of host-guest interaction is investigated. The reversible disassembly-reassembly of the polymer induced by light and the redox process are monitored by UV-vis and cyclic voltammetry, respectively...
August 16, 2017: Macromolecular Rapid Communications
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